Terms of Reference
I wrote this Report specially for our
students , because many of us have a little information about this important
theory , this Report was written according to many scientific theory and Research
without any self opinion.
As far as iam concerned this report may not offer a proper
information about this topic but somehow it can help students to get a bit more
information about it , so I hope to heat my target which is helping students to
get more experience .
Abstract ( Summary
The Big Bang Theory is a cosmological
theory explains that how universe began from a very small point , The aim of
this Report is to describe and explain Big Bang theory, and the aim of the
Theory is to observe that all matter and universe was concentrated in a small point
before 13.7 billion years ago, and then began to expansion with a hot explosion
and till today the universe expanding without any limit , one of the most
important points that needs to be mentioned is , this Theory isn’t a religious
topic but it’s a collection of too many researches that were worked on by a plenty of scientists
and it became a scientific theory .
Terms of Reference 1
Abstract ( Summary ) 1
What happen in
the first second after the universe began ? 3-4
Expansion of universe
Features of models 6
did all the scientist support Big bang theory ?
How old is the universe ?
– Reference List
Along the history humans always have a some
questions about the beginning of the universe include : How did our universe
begin? How old is our universe? How did matter come to exist? Obviously, these
are not ordinary questions and throughout our brief history on this planet much
time and effort has been spent looking for some clue. Yet, after all this energy
has been expended, much of what we know is still only speculation. But Big Bang
Theory can help us to understand our Universe . Today,
the consensus among scientists, astronomers and cosmologists is that the
Universe as we know it was created in a very big explosion,
Big Bang Theory is the most important
cosmological Theory that wants to explain what happened at the very beginning
of the universe, and wants to observe that our universe have a beginning , The basics of the
theory are very simple. In brief , the Big Bang hypothesis states that all of
the current and past matter in the Universe came into existence at the same
time, roughly 13.8 billion years ago. At this time, all matter was compacted
into a very small ball with infinite density and intense heat called a
Singularity. Suddenly, the Singularity began expanding, and the universe as we
know it began . seriously this theory does not observe everything like (Dark
Energy) and till now the scientist can not explain completely what is Dark Matter , and also some of
scientist do not believe and do not support this Theory and some of them have
an alternative , this Theory is still developing and till now the research are
One of the most continuing
asked questions has been: How was the universe created? Many once believed that
the universe had no beginning or end . but Big Bang Theory refused this idea
completely and emphasized that Universe has a beginning and an end .
Regarding to Big Bang Theory , At the
beginning the whole universe was just a small point that had an extreme high
temperature and high density , but at about 13.7 billion years ago the universe begun to expansion with a
What happened in the first
second after the universe began ?
In the first
second after the universe began, the temperature was nearly 10 billion degrees
Fahrenheit (5.5 billion Celsius) ,The cosmos consisted of a wide array of
fundamental particles for instance , neutrons , electrons and protons. These
decayed or combined as the universe got cooler. But imagine that light could not carry inside of it , how can you look at it ?
After the initial expansion the universe
cooled sufficiently to allow the formation of subatomic particles, and later
simple atoms , these primordial elements later coalesced through gravity in halos of dark matter , ongoing forming the stars and galaxies
obvious today . “The free electrons would have caused light
(photons) to scatter the way sunlight scatters from the water droplets in
clouds” Over time, however, the free electrons met up with nuclei and
created neutral atoms . This allowed light to shine through about 380,000 years
after the Big Bang.
This light is known as (after glow)of
the big bang.
The universe continued to minimize in density
and fall in temperature , hence the typical energy of each particle was
decreasing . Symmetry
transitions put the fundamental forces of physics and the parameters of elementary particles into their exist form
. After about 10?11 seconds, the picture turns to less speculative,
since particle energies drop to values that can be attained in particle accelerators. At about 10?6 seconds,
quarks and gluons combined to form baryons such as protons and neutrons. The small
excess of quarks over antiquarks led to a small excess of baryons over
antibaryons. The temperature was now no longer high enough to create new
proton–antiproton pairs (similarly for neutrons–antineutrons) , so a mass annihilation
suddenly followed, leaving just one in 1010 of the original
protons and neutrons, and none of their antiparticles. A similar process occurred
at about 1 second for electrons and positrons. After these annihilations, the left
protons, neutrons and electrons were no longer moving relativistically and the
energy density of the universe was dominated by photons (with a minor contribution from neutrinos).
A few minutes into the expansion, when the
temperature was about a billion (one thousand million) kelvin and the density was about that of air , neutrons
combined with protons to form the universe’s deuterium and helium nuclei in a process called Big Bang
protons remained uncombined as hydrogen nuclei.
As the universe cooled, the rest mass energy density of matter came to
gravitationally dominate that of the photon radiation . After nearly 379,000
years , the electrons and nuclei combined into atoms (mostly hydrogen); hence
the radiation decoupled from matter and continued through space grately
unimpeded . This relic radiation is known as the cosmic
microwave background radiation . The chemistry of life may have begun shortly after the Big
Bang , 13.8 billion years ago, during a habitable epoch
when the universe was just 10–17 million years old.
Expansion of universe
energy is even more mysterious, and its discovery in the 1990s was a complete surprise
to scientists. Previously, physicists had assumed that the beauty force of
gravity would slow down the expansion of the universe over time. But when two
independent teams tried to measure the rate of deceleration, they found that
the expansion was definitely speeding up.
University contains of 3 basic types of
matter ( Dark Energy , Dark Matter , Ordinary Matter )
What is Dark Energy ?
More is unknown than is known . We know
how much dark energy there is because we know how it affects the universe’s
expansion. Other than that , it is a complete mystery . But it is an important
mystery . It turns out that almost 68% of the
universe is dark energy . One explanation for dark energy is that it is a
property of space. Albert Einstein was the first person to identify that empty
space is not nothing. Space has wonderful characteristic , many of which are
just beginning to be understood. The first property that Einstein found is that
it is suitable for more space to come into existence . Then one version of
Einstein’s gravity theory , the version that contains a cosmological
constant , makes a
second prediction: “empty space” can possess its own energy. Because
this energy is a property of space itself , it would not be diluted as space
expands . As more space comes into existence, more of this energy-of-space would
appear , As a result, this form of energy could cause the universe to expand
faster and faster.
What is Dark Matter
We are much
more certain what dark matter is not than we are what it is . First, it is dark
, meaning that it is not in the form of stars and planets that we can see . notices
show that there is far too little visible matter in the universe to make up the
27% required by the observations . Second , it is not in the form of dark
clouds of normal matter , matter made up of particles called baryons. We know
this because we would be able to detect baryonic clouds by their absorption of
radiation passing through them . Third, dark matter is not antimatter , because
we do not see the unique gamma rays that are produced when antimatter
annihilates with matter.
In all in ,
the continuous expansion of Universe is totally because two primary things ,
Dark Energy and Dark Matter.
Ordinary Matter ?
look at the sky at night what do you see ? stars , planets and all other kind of Matters
in the Universe are known as Ordinary matter .
Features of the model
Big Bang theory relays on two main assumptions: the universality of physical
laws and the cosmological principle . The cosmological principle states that on large scales
the universe is homogeneous and isotropic.
views were initially taken as postulates , but today there are efforts to test
each of them . For example , the first assumption has been tested by
observations showing that largest possible deviation of the fine structure constant over much of the age of the universe is
of order 10?5. Also , general relativity has passed stringent tests on the scale of the Solar System and binary stars.
the large-scale universe appears isotropic as viewed from Earth , the
cosmological principle can be derived from the simpler Copernican principle , which states that there is no preferred (or special)
observer or vantage point. To this end , the cosmological principle has been approved
to a level of 10?5 via observations of the CMB. The universe
has been measured to be homogeneous on the biggest scales at the 10% level.
did all the scientists support Big bang theory
Of course no ,
in 1948 British scientists , Sir Hermann Bondi, Thomas Gold, and Sir Fred Hoyle . presented a
new theory , in their opinion this could
be as an alternative to Big Bang theory which named (Steady State Theory).
What is Steady
State Theory ?
In cosmology, the Steady State
theory is an alternative to the Big Bang model of the evolution of our universe. In the 1940s Sir Fred Hoyle and others developed an alternative
mathematical model of the Universe that did not begin in a large expansion . They
said that matter is eventually created at a rate that keeps the average density
of the Universe the same as it expands . Though the Steady State theorists’
ideas are largely discredited today , their research pushed the Big Bang
supporters to back up their theory with evidence.
amazingly , it was
Hoyle who coined the term Big Bang in an attempt to put down the idea that the
Universe had a beginning . According to the
Steady State Theory , one of its items which is fully against the Theory of Big
Bang is that Universe has neither a beginning of its creation nor a deadline
How old is the universe
may only be a number, but when it comes to the age of the universe , it’s a
pretty important one . According to research , the universe is approximately
13.8 billion years old . How did scientists determine how many candles to put
on the universe’s birthday cake ? They can determine the age of the universe
using two different forms : by studying the oldest subject within the universe
and measuring how fast it is expanding.
we understood that our universe was came from a small singularity which have an
extreme high temperature and density and then , and immediately before 13.8
billion years the universe faced an explosion , after this great explosion the
universe started cooling , and expanding .
Universe is contain of (Dark Energy , Dark Matter , Normal Matter)
our University is Dark Energy that caused the Universe to expand
of our Universe is Dark Matter , which is not in the same form stars
and planets that we see
5% of our University is normal matter ,
such as stars and planets and all kind of Matter that we can see and describe
And Big Bang is not only Theory of how
the universe came from begin for example, there is the Steady State
1- ( The Theory of everything ) Stephen
The big bang theory is vastly accepted
because there is strong evidence in its favour, and because it arises naturally
from the General Theory of Relativity , which is itself a well-tested theory .
There have been several alternative models since the Big Bang was proposed in
the late 1940s, but most of them failed observational tests. There is one
currently supported alternative theory , which is more hard to test , but
relevant evidence should be forthcoming in the subsequent few years.
What are the
major clue which support the Big Bang theory?
First of all,
we are reasonably certain that the universe had a beginning.
galaxies appear to be moving away from us at speeds proportional to their
distance . This is called “Hubble’s Law,” named after Edwin
Hubble (1889-1953) who discovered this phenomenon in 1929. This
observation gets behind the expansion of the universe and suggests that
the universe was once compacted.
Third , if the
universe was initially very, very hot as the Big Bang suggests , we should
be able to find some remnant of this heat . In 1965, Radio astronomers
Arno Penzias and Robert Wilson discovered a 2.725 degree Kelvin (-454.765
degree Fahrenheit , -270.425 degree Celsius) Cosmic Microwave Background
radiation (CMB) which pervades the observable universe. This is thought to
be the remnant which scientists were searching for. Penzias and Wilson
shared in the 1978 Nobel Prize for Physics for their discovery.
Finally , the
abundance of the “light elements” Hydrogen and Helium found in
the observable universe are thought to support the Big Bang model of